If you are working on models that you want to publish to your website then you can create a web service that you would only have to authorize once, and from then onwards it could keep acces...
Model Derivative API has been able to extract AEC data of Revit model such as level, grid, views, phase, linked documents etc. And Forge Viewer also provides the corresponding methods
...
When selecting multiple objects in the UI then the behaviour of the Property Palette (i.e. which object's properties the palette is showing) can seem a bit random.